1. Technical Field
The disclosure relates to communications and, more particularly, to signaling of resource allocations.
2. Discussion of Related Art
Abbreviations
    3GPP Third generation partnership project    BPSK Binary Phase Shift Keying    CDM Code Division Multiplexing    CP Cyclic Prefix    CRC Cyclic Redundancy Check    eNode-B Evolved Node B    E-UTRAN Evolved-UTRAN    FEC Forward Error Correction    FDD Frequency Division Duplex    FDPS Frequency Domain Packet Scheduling    FDMA Frequency Division Multiple Access    HARQ Hybrid Automatic Repeat Request    LTE Long Term Evolution    MAC Medium Access Control    MIMO Multiple Input Multiple Output    OFDM Orthogonal Frequency Division Multiplexing    OOK On-off keying    PBCH Physical Broadcast Channel    PCFICH Physical Control Format Indicator Channel    PDSCH Physical Downlink Shared Channel    PDCCH Physical Downlink Control Channel    PHICH Physical Hybrid ARQ Indicator Channel    PMCH Physical Multicast Channel    PRACH Physical Random Access Channel    PUCCH Physical Uplink Control Channel    PUSCH Physical Uplink Shared Channel    Q Quadrature    QAM Quadrature Amplitude Modulation    QPSK Quadrature Phase Shift Keying    RACH Random Access Channel    RLC Radio Link Control    RR Resource Request    RRC Radio Resource Control    RSSI Received Signal Strength Indicator    RSRP Reference Signal Received Power    RSRQ Reference Signal Received Quality    SAP Service Access Point    SC-FDMA Single-Carrier Frequency Division Multiple Access    SF Spreading Factor    SNR Signal to Noise Ratio    SR Scheduling Request    TDD Time Division Duplex    TTI Transmission Time Interval    UL Uplink    UTRAN Universal Terrestrial Radio Access Network
Control signaling is known in general and serves many purposes in communications systems. Such may include signaling the allocation of communication resources made between a network element and a plurality of terminals. Each terminal may have a constant or varying need for communicating data with the network element in either direction. To distribute the data there may be a need to protect against time-varying adverse communication channel conditions by allocating the data intended for a given terminal to various communication resource elements that are dynamically changed in various domains such as time, frequency and space.
Both the control signaling and the data can be dynamically allocated in this way within various bandwidths. In other words, it can be the case that a certain amount of resources is set aside for signaling and another corresponding amount of resources for data. To give such a system more flexibility, it can be the case that a plurality of certain resources is designed for signaling and another plurality of corresponding resources is designed for data. A pair of a signaling resources and a data resources would be chosen and set aside for use by a particular network element and associated terminals for a particular circumstance. In the above discussion the term resources refers to a set of physical resources which are to be transmitted over an interface. This interface could for instance be a wireless air interface. The physical resources could be, but is not limited to, for instance a set of sub-carrier symbols in an OFDM system. Aspects of the physical layer of an exemplary Radio Access Network that uses OFDM are described in 3GPP TS 36.201 V1.2.0 (2007 June), TS 36.211 V1.2.0 (2007 June), 36.212 V1.3.0 (2007 July) and 36.213 V1.20 (2007 May). See for instance the Frame structure in section 4, the Downlink of section 5 (a downlink resource grid is shown in FIG. 3), and the Uplink of Section 6 (two uplink slot formats shown in FIGS. 15 and 16) of 3GPP TS 36.211 V1.2.0 (2007 June).
For example, in case of a direction from the network element to the terminals and assuming the signaling/data bandwidth pair is chosen and known at both the network element and the associated terminals, the network element could send resource allocation signaling to all of the terminals in such a way that each terminal can locate its own allocation information so that it can subsequently obtain information on how to find, demodulate, and decode data also sent from the network element to all terminals but each terminal only extracts the information that is specifically intended for it. Such a one-to-many communication scenario requires that a search of the control signaling be conducted by each terminal for a pointer to the placement of the resource element or elements containing its data that is about to be sent from the network element.
It can be the case that the network element is in possession of identifying information concerning each associated terminal and can use such information to designate which control and data resource elements belong to a given terminal. Since the terminal will be in possession of its own identifier as well, it can search the control signaling resources to find its control information and each other terminal can do the same. Once the pointers are obtained in this way, the terminals can find their data in data resources within the bandwidth that is set aside for data.
It can be burdensome for the terminal to have to search through all of the signaling resources within which its own signaling may be found. Various techniques to reduce the search burden have been proposed and will have a beneficial effect when adopted. For instance, it may be possible to reduce the searching burden by half or more by using certain strategies.
The beneficial effect of such strategies could be blunted, however, if additional complexity is introduced to the signaling. For example, additional proposals have been made to use a more complex signaling structure that includes differently sized signaling is used for different terminals in communication with the network element. Such might be used in a case where one terminal is to receive only a single data stream and another terminal is to receive more than one data stream at the same time. Other examples of different payload sizes include, but are not limited to, uplink resource allocation signaling, uplink power control commands, and resource allocations for a downlink shared channel. For the exemplary downlink described below, the possibility of differently sized signaling resources being signaled for different terminals multiplies the search task burden imposed on the terminals.